Merge pull request #14 from nnethercote/fix-JSON-handling-more

Fix JSON handling more

src/main.rs

@@ -53,7 +53,7 @@ impl Interner {
     }
 }
 
-enum JsonEscaping {
+enum JsonMode {
     No,
     Yes,
 }
@@ -252,22 +252,23 @@ impl FileInfo {
 struct Fixer {
     re: Regex,
     file_infos: FxHashMap<String, FileInfo>,
-    json_escaping: JsonEscaping,
+    json_mode: JsonMode,
 }
 
 /// Records address of functions from a symbol table.
 type SymFuncAddrs = FxHashMap<String, u64>;
 
 impl Fixer {
-    fn new(json_escaping: JsonEscaping) -> Fixer {
+    fn new(json_mode: JsonMode) -> Fixer {
         Fixer {
             // Matches lines produced by MozFormatCodeAddress().
             re: Regex::new(r"^(.*#\d+: )(.+)\[(.+) \+0x([0-9A-Fa-f]+)\](.*)$").unwrap(),
             file_infos: FxHashMap::default(),
-            json_escaping,
+            json_mode,
         }
     }
 
+    /// Add JSON escapes to a fragment of text.
     fn json_escape(string: &str) -> String {
         // Do the escaping.
         let escaped = serde_json::to_string(string).unwrap();
@@ -276,6 +277,20 @@ impl Fixer {
         escaped[1..escaped.len() - 1].to_string()
     }
 
+    /// Remove JSON escapes from a fragment of text.
+    fn json_unescape(string: &str) -> String {
+        // Add quotes.
+        let quoted = format!("\"{}\"", string);
+
+        // Do the unescaping, which also removes the quotes.
+        let value = serde_json::from_str(&quoted).unwrap();
+        if let serde_json::Value::String(unescaped) = value {
+            unescaped
+        } else {
+            panic!()
+        }
+    }
+
     /// Read the data from `file_name` and construct a `FileInfo` that we can
     /// subsequently query. Return a description of the failing operation on
     /// error.
@@ -547,11 +562,19 @@ impl Fixer {
         let address = u64::from_str_radix(&captures[4], 16).unwrap();
         let after = &captures[5];
 
+        // In JSON mode, unescape the function name before using it for
+        // lookups, error messages, etc.
+        let raw_in_file_name = if let JsonMode::Yes = self.json_mode {
+            Fixer::json_unescape(in_file_name)
+        } else {
+            in_file_name.to_string()
+        };
+
         // If we haven't seen this file yet, parse and record its contents, for
         // this lookup and any future lookups.
-        let file_info = match self.file_infos.entry(in_file_name.to_string()) {
+        let file_info = match self.file_infos.entry(raw_in_file_name.to_string()) {
             Entry::Occupied(o) => o.into_mut(),
-            Entry::Vacant(v) => match Fixer::build_file_info(in_file_name) {
+            Entry::Vacant(v) => match Fixer::build_file_info(&raw_in_file_name) {
                 Ok(file_info) => v.insert(file_info),
                 Err(op) => {
                     // Print an error message and then set up an empty
@@ -561,32 +584,32 @@ impl Fixer {
                     //   first occurrence.
                     // - The line will still receive some transformation, using
                     //   the "no symbols or debug info" case below.
-                    eprintln!("fix-stacks error: failed to {} `{}`", op, in_file_name);
+                    eprintln!("fix-stacks error: failed to {} `{}`", op, raw_in_file_name);
                     v.insert(FileInfo::default())
                 }
             },
         };
 
-        // If JSON escaping is enabled, we need to escape any new strings we
-        // produce. However, strings that came in from the text (i.e.
-        // `in_func_name` and `in_file_name`), will already be escaped, so if
-        // they become part of the output they shouldn't be escaped.
+        // In JSON mode, we need to escape any new strings we produce. However,
+        // strings from the input (i.e. `in_func_name` and `in_file_name`),
+        // will already be escaped, so if they are used in the output they
+        // shouldn't be re-escaped.
         if let Some(func_info) = file_info.func_info(address) {
-            let raw_func_name = func_info.demangled_name();
-            let out_func_name = if let JsonEscaping::Yes = self.json_escaping {
-                Fixer::json_escape(&raw_func_name)
+            let raw_out_func_name = func_info.demangled_name();
+            let out_func_name = if let JsonMode::Yes = self.json_mode {
+                Fixer::json_escape(&raw_out_func_name)
             } else {
-                raw_func_name
+                raw_out_func_name
             };
 
             if let Some(line_info) = func_info.line_info(address) {
                 // We have the function name, filename, and line number from
                 // the debug info.
-                let raw_file_name = file_info.interner.get(line_info.path);
-                let out_file_name = if let JsonEscaping::Yes = self.json_escaping {
-                    Fixer::json_escape(&raw_file_name)
+                let raw_out_file_name = file_info.interner.get(line_info.path);
+                let out_file_name = if let JsonMode::Yes = self.json_mode {
+                    Fixer::json_escape(&raw_out_file_name)
                 } else {
-                    raw_file_name.to_string()
+                    raw_out_file_name.to_string()
                 };
 
                 format!(
@@ -622,19 +645,19 @@ r##"usage: fix-stacks [options] < input > output
 Post-process the stack frames produced by MozFormatCodeAddress().
 
 options:
-  -h, --help      show this message and exit
-  -j, --json      Use JSON escaping for printed function names and file names
+  -h, --help      Show this message and exit
+  -j, --json      Treat input and output as JSON fragments
 "##;
 
 fn main_inner() -> io::Result<()> {
     // Process command line arguments.
-    let mut json_escaping = JsonEscaping::No;
+    let mut json_mode = JsonMode::No;
     for arg in env::args().skip(1) {
         if arg == "-h" || arg == "--help" {
             println!("{}", USAGE_MSG);
             return Ok(());
         } else if arg == "-j" || arg == "--json" {
-            json_escaping = JsonEscaping::Yes;
+            json_mode = JsonMode::Yes;
         } else {
             let msg = format!(
                 "bad argument `{}`. Run `fix-stacks -h` for more information.",
@@ -646,7 +669,7 @@ fn main_inner() -> io::Result<()> {
 
     let reader = io::BufReader::new(io::stdin());
 
-    let mut fixer = Fixer::new(json_escaping);
+    let mut fixer = Fixer::new(json_mode);
     for line in reader.lines() {
         writeln!(io::stdout(), "{}", fixer.fix(line.unwrap()))?;
     }

src/tests.rs

@@ -31,7 +31,7 @@ fn test_linux() {
     //   LINE 0x11cd line=13 file=/home/njn/moz/fix-stacks/tests/example.c
     //   LINE 0x11db line=14 file=/home/njn/moz/fix-stacks/tests/example.c
 
-    let mut fixer = Fixer::new(JsonEscaping::No);
+    let mut fixer = Fixer::new(JsonMode::No);
 
     // Test various addresses.
     let mut func = |name, addr, linenum| {
@@ -62,7 +62,7 @@ fn test_linux() {
     func("g", 0x11de, 14);
 
     // Try a new Fixer.
-    fixer = Fixer::new(JsonEscaping::No);
+    fixer = Fixer::new(JsonMode::No);
 
     // Test various addresses outside `main`, `f`, and `g`.
     let mut outside = |addr| {
@@ -110,7 +110,7 @@ fn test_windows() {
     // outputs contains backwards slashes, though, because that is what is used
     // within the debug info.
 
-    let mut fixer = Fixer::new(JsonEscaping::Yes);
+    let mut fixer = Fixer::new(JsonMode::Yes);
 
     // Test various addresses using `example-windows`, which redirects to
     // `example-windows.pdb`.
@@ -142,8 +142,8 @@ fn test_windows() {
     func("g", 0x6c49, 12);
     func("g", 0x6c63, 14);
 
-    // Try a new Fixer, without JSON escaping.
-    fixer = Fixer::new(JsonEscaping::No);
+    // Try a new Fixer, without JSON mode.
+    fixer = Fixer::new(JsonMode::No);
 
     // Test various addresses outside `main`, `f`, and `g`, using
     // `example-windows.pdb` directly.
@@ -229,7 +229,7 @@ fn test_mac() {
     //   LINE 0xf38 line=10 file=/Users/njn/moz/fix-stacks/tests/mac-lib2.c
     //   LINE 0xf49 line=11 file=/Users/njn/moz/fix-stacks/tests/mac-lib2.c
 
-    let mut fixer = Fixer::new(JsonEscaping::No);
+    let mut fixer = Fixer::new(JsonMode::No);
 
     // Test addresses from all the object files that `mac-multi` references.
     let mut func = |name, addr, full_path, locn| {
@@ -266,7 +266,7 @@ fn test_mac() {
 
 #[test]
 fn test_regex() {
-    let mut fixer = Fixer::new(JsonEscaping::No);
+    let mut fixer = Fixer::new(JsonMode::No);
 
     // Test various different unchanged line forms, that don't match the regex.
     let mut unchanged = |line: &str| {
@@ -301,7 +301,7 @@ fn test_regex() {
 
 #[test]
 fn test_files() {
-    let mut fixer = Fixer::new(JsonEscaping::Yes);
+    let mut fixer = Fixer::new(JsonMode::Yes);
 
     // Test various different file errors. An error message is also printed to
     // stderr for each one, but we don't test for that.